I do not agree the the first person to give public expression and be recorded for history, alone gives a high probability

I didn't say "high probability", I said "relatively high". By which I mean it is high relative to some baseline in which we don't know anything, or relative to the second case. In other words, what I am saying is that if a person is the first to give public expression, this is evidence that he originated it.

I only know Quine through what little I have read here and wikipedia and did not judge it original enough

Many others thought it  highly original. Also, I'm not confident that you're in a position to make that judgment. You would need to be pretty familiar with the chronology of ideas to make that call, and if you were, you would probably be familiar with Quine.